Bay is looking because knowing her father and who he is helps her to know who SHE is. She has recently found out that all that she knows, all that she thought defined her, wasn't REALLY hers. So now she's trying to figure out who she would have been, and where she came from. A big part of that is knowing who both her parents are, because knowing who her parents are helps to tell her who she is. I have friends who haven't looked for their biological parents either, but chances are they've grown up for most of their lives accepting the fact that they don't have two solid parents and are accustomed to the fact and don't have any desire to know. Daphne has learned to define herself by her mother and grandmother, or at least who she thought were her mother and grandmother. Bay doesn't have that. Regina isn't hugely open to getting to know Bay the way the Kennishes want to know Daphne, so Bay needs something else to connect with. Sorry for the long response, but I'm on Bay's side with going to look for him.