My own informal survey seems to indicate that DOB and place of birth are changed in 10-30% of the cases. but this high a number may be limited to selected localities. So if you if you want to find someone, don't depend entirely on vital data being exactly right.

(One survey put adoption in another state at about 18% for just b-mothers requesting the change, and with agencies doing this themselves, who knows? 25%, 35% 45%? And DOB changes are likely to be in the 10-25% range. But this survey was based on those who searched hard enough to uncover this. Some do not search hard enough so these numbers could be lower than reality.)

Some adoptees find it hard to believe their DOB is not what they have celebrated all their life. But this emotional difficulty must be overcome, if one is to find a birth parent.

Now, the courts can order dates and places and names changed, but they cannot change your DNA. So the way to find someone is to match blood DNA. However, this costs money. So before you spend it, you need real convincing proof you have the right person, before taking such a test. 

Now if two persons are searching and should be looking in the same registry or bulletin board on the internet, they can find each other if they follow the following procedure. This procedure is best described as "building on your successes".

APPROXIMATE DOB, ANY STATE (OR COUNTRY)
First, you can use an approximate date to find someone, provided they are also looking. Unless you are in a state that has open records you can only use internet bulletin boards and registries or pay outrageous fees for someone to search. But searchers are "lazy" and usually only look for an exact DOB match. They do not "dig" to find out if the DOB and place of birth was changed. (Such digging costs real money, not the mere $20-100 some ask for, and which you are likely throwing away, but you can look in the same databases as well, usually for free.)

START A DIALOGUE WITH EACH POSSIBLE PERSON (E-MAIL)
Second, if you find someone who has a birth date within about one year of when you think the birth occurred, you can explain your situation to whom ever you contact and start asking about inheritable traits. (Tell this person that DOB and place of birth do not have to match closer than about one year since these are very often changed anyway.) Also, remember, only about 3% of the population is adopted, or 1.5% of the total population for each sex, and so if you get within one year, you can know that this improves your chances significantly. But this could still leave tens of thousands of persons.

COMPARE ALL INHERITIABLE TRAITS
Third, if you come up with 20-30 inheritable traits, then you have at least a "lead".  Now questions for inheritable traits include hobbies, careers, natural skills, things people like to collect, names of pets, family members names and the list goes on and on. Make your list as large as possible. This would justify exchanging photos and full-page handwriting samples, writing down the same text to make comparison easier. At this point you could be down to just a few thousand possibilities, if you seem to find enough in common. (Note: Identical twins have behavior that is typically 70-80% identical, while siblings and children have behavior that is typically 30-40% identical and is attributed solely to genetic inheritance. Source: research done in England on identical twins, separated at birth, but raised by separate and parents with different traits.)

PHOTOS AND HANDWRITING
Fourth, photos and handwriting should be compared between all blood relatives. There is a handwriting analysis book for $7.00. The analysis is very easy. If you come up with about a 70% match, you have a match. (You are not trying to determine what personality two persons have, only that they are nearly identical.) As for photos, you look for eye and hair color, ears and nose and mouth shapes, jaw and chin bones, etc, etc. Keep in mind that children have mixtures of features of both parents. If you have some good photo matches between various blood relatives and some handwriting matches, you could now be down to just a few hundred possibilities.

MEDICAL TRAITS
Fifth, consider any inheritable medical problems, including vision, hearing, heart, spinal, mental, disease, etc. Also consider blood types.

ADOPTION CIRCUMSTANCES
Sixth, consider any circumstances surrounding the adoption. Are there any similarities? If any circumstances are contrary, but are the kind that agencies, courts, lawyers, etc, could change, then ignore them!
Only pay attention to what matches. (What does not match can be resolved later.) By now you could be down to just a few possibilities, but you could also have overwhelming evidence by now. (Maybe a DNA test is not even needed.)

DNA TEST
Seventh, if you think you have a "match", then you can always do a maternity or paternity DNA blood test. This can even work to some extent for siblings. But before you spend the money, be sure to have done as much investigation of matching traits and so forth so that you have every confidence the DNA test will prove to be a match. Try to leave "no stone unturned" in all your investigation. This will spare you the expense of a DNA test that is negative.

Searchers have got to take seriously the fact that relocation is a very real possibility. Even DOB changes have occurred. If you are b-mother, there perhaps a 40% chance your child was moved to another county in the state, or even to another state without them telling you about it. If you are an a-child, then you have to broaden your search, first to the entire state, or even several surrounding states. You have to keep an open mind to the possibility of a DOB change. Now all this depends on variables like location, time period, and so forth.

Here are the things I have uncovered in my 2 years of searching:

A formal survey at a TRIAD site reported that 9 out of 50 b-mothers surveyed, that's 18%, asked for and got their child adopted in another state.

If you are one of these b-mothers, then you already know to look in other states. If you are an a-child, you have no way to know this so don't dismiss the possibility, especially an 18% possibility.

There have been a number of adoption scandals throughout the history of adoption. These often involve changes to location and DOB to help hide the "crime".

As an a-child, you have no idea if your adoption was the product of some scandal. Even a few b-mothers were told the child died giving birth, but didn't and the child was put up for adoption.

There have been a number of kidnappings in which young children were then adopted.

Were you a child kidnapped from your parent(s)? How do you know you were not. You don't unless you were old enough to remember.

Throughout the history a number of nationwide adoption "chains" have existed. Among these is Catholic Charities and Crittenden Homes. Many other religious groups have had adoption agencies. There were also many orphanages, especially in the past. Then you have the state agencies. All of these together form "adoption networks". These agencies have one goal in mind: adoption. First, the child needs a secure home. Second, it cost money to care for children in the agency's facilities. Third, childless parents have this need to adopt.

Given all these factors, agencies are motivated to see that adoptions occur without too much delay, other than the customary process of adoption. So, these agencies are indeed motivated to move children to other locations for adoption, if need be. If one region or area has a shortage of children to adopt and a surplus of potential parents, and another region has a surplus of children to adopt but a shortage of potential parents, then its simply a matter of practicality to see to it a child is adopted, no matter what locality it is in. Emotionally, agents do not want to see a child be homeless for too long.

Financially, it can be cheaper to transport a child to another locality than to care for a child day after day when there are few prospects for adoption in one locality, but plenty in another. 

Given the inter- and intra-agency networking available to adoptionagencies, relocating for adoption is really not a big deal. So depending on location, time period and other demographics, many children have throughout the history of adoption been relocated. And with relocation, the new birth certificate shows the new location as the place of birth, since virtually all state laws permit this.

Both b-parents and b-children should consider looking nationwide, although one should consider the same location first, then adjacent counties, then adjacent states, then nearby states and then the rest of the country. This method follows highest probabilities.

While I have seen a number of reunifications where DOB is the same as well as location, I have also heard from a number of adoptees and b-parents that located each other and discovered the changes made, most frequently location was changed, but occasionally DOB. Some have been moved several states away, one even from the USA to Canada. 
Others have reported to me change in DOB of a few days, and one guy reported over one year!
This, I fear, is only the "tip of the iceberg". The problem is that not enough people search hard enough. Far too many look only for exact location and exact DOB. So the real statistics are not known.

Do you know for sure your DOB is accurate? Do you know for sure your place of birth is correct? How do you know? The records are sealed. So how do you know? You don't. You have only the amended BC if you are an adoptee and since most state laws permit the amended BC to reflect the place of birth to be the county and state your a-parents were living in at the time of adoption, how do you know? You don't. In fact, if the agency moved a child in from another state where children are more in demand, then even the a-parents do not know the truth.

Throughout adoption history, no doubt many a b-mother has changed her mind after giving a child up for adoption. One motivation for sealing records then, was to keep the birth mother from one day finding the child and possibly "kidnapping" the child, or causing an emotional mess for the child when the child sees or hears from his/her b-mother/father. But sealed records and a name change seems to not be enough. If the location and the DOB is the same, and the location is a sparsely populated area, then it would be relatively easy for a b-parent to find their child, even with a total name change. The b-parent could just, for example, look at children at the local elementary school, see a child that has the right facial features, walk up to the child and ask his/her DOB. Chances are this is this person's natural child. So in sparsely populated areas, a name change and sealed records was/is likely not enough. Hence, relocation at a minimum and even changing a DOB by a few days or weeks helps prevent the problems associated with a b-parent finding his/her child. 

Now if you are a b-mother and your child was born in a sparsely populated area, then you better look elsewhere. But if you are an a-child, you have no idea. Even if you have a BC that says you were born in a large city like Chicago, New York or Los Angeles, you could have been moved there from a sparsely populated area to a local adoption agency.

Some regions of the country are/were relatively "poor". While adoption agencies, possibly by law, have to consider even low-income parents as being potentially "good parents", let's face it, private agencies and even the not so private have to operate in the black, not the red.
Hence, financial considerations do not only include whether or not the prospective parents have the income to care for a child, but also to pay the cost of the adoption. True, state agencies may help to pay the bill, but even they prefer "paying customers". In any cases, children available for adoption tend to gravitate towards where the money is, which means away from poorer areas of the country towards better-off areas. Hence, change of location of birth on the BC.

Do you know as an adoptee that your b-parents did not live in a low-income area of the country? You don't know. As a b-parent, if you at the time of birth did live where incomes were low, chances are you need to look in another locality.

Some adoptees would think, well at least my agency was Catholic or Methodist or whatever. So my b-parents must have been too. Well, apparently this is mostly true, but not always. First of all, religiously speaking, conversion is a preferable goal. Hence, for a Catholic agency to take in say a Jewish child and give the child to Catholic parents, is certainly desirable. Next, private agencies do not care if a religious preference is maintained. (My friend is Catholic. She asked a private agency, Crittenden Homes, to insure her child would be raised Catholic. The child was raised Jewish instead.

It seemed being paid was more important to this agency, that respecting the b-mother's wishes.)

Because you are raised by your by your a-parents who are of a particular religion, how do you know for sure your b-parent(s) were the same? You don't. Likewise, because you gave your child up to an agency, or even a religious group, how do you know they did not give the child up to parents of another religious persuasion or even sent the child elsewhere to be adopted? You don't.

Because of the fear that abusive parents, adjudicated to be "unfit" might abuse their children should they find them again and kidnap them, once a judge has signed the order, it really is indeed in the best interest of the child to move the child to another location for adoption. If the child is still a toddler, then even a slight DOB change in addition to adoption in a new locality is the best way to protect a child from abusive parent(s). Hence the BC will again reflect these changes. Most states will change location and/or DOB "in the best interest of the child.(My ex-wife was taken from abusive parents and adopted.)

How do you know that you were not adopted because your b-parent(s) were abusers and you had to be moved to another location for your own safety? (Now if your parents are rehabilitated and/or you are old enough to be "safe" you may still need closure with them as a motive to meet them, but of course you have no way of knowing this with a sealed record system.)

In some areas of the country, if the b-mother/father are of a certain nationality, the color of their skin, eyes, hair, etc, may be a "dead give-away". So to prevent a b-parent from finding the child through this method, again the child may be moved to a locality far enough away so the child blends in, or is just too far to be found.

Is this you?

Adoption is meant to be final. The b-parent(s) give up all rights to the child. But law is one thing and emotion another. B-parent(s) who change their mind and search, even in big cities where a child would be hard to find, still may have friend's on the police force, friend's in the government (I once had a friend who worked at vital records), friends in power, or pay a P.I. with contacts. Adoption agencies aware of this, realize once again moving the child to another locality makes it nearly impossible for a searching b-parent to find the child, since a searching b-parent would need a friend in every county in the country.

Could this be you?