I can only speak from my own experience, but I know for a fact that there is a hole in my identity left by the fact that I know I have biological parents out there but don't know anything about them - what they look like, how they sound, how their lives have unfolded.
Regardless of the rational and logical reality that their DNA don't really 'matter' in the grand scheme of things, I cannot deny that as a human being who is self-aware, and by the simple fact that I observe people who are biologically related and clearly see how that manifests itself in their identities, I feel incomplete and have lots of questions that simply cannot be answered any other way than by meeting the bio-rents.
A lot of people want to make it 'OK' by using the DNA doesn't matter line of logic, but as 'correct' as it may be, that's just not enough.
As a person who has lived his entire life wondering what bio-mom and bio-dad at least look like, the ONLY time I felt what I assume is the 'connection' biologically related people feel was when my daughter was born. That was the first time I'd EVER (to my knowledge) seen another person who I share DNA with - ever. That was the first time I didn't feel genetically isolated in 33 trips around the sun.
Regardless of what my bio-rents are 'like' - whether they are 'good/bad' people - it doesn't matter. Being in proximity to a person you share DNA with tells you stuff that words and logic don't. It may not provide me with a sense of completion or satisfaction, - hell, it may even be disappointing - but not knowing definitely leaves a hole.
