How can I reason with my wife about this?

Wife and I have been married for about 3 years now, before we hadn't discussed about kids because we thought we should wait and also before she had stated she only would want to adopt. As of lately we have both talked about having kids, Mostly because she has gone into "Baby mood" for lack of a better term and has talked about wanting to become pregnant. My Wife and I are both Adopted and know very little about a background Medical history, such as what runs in our biological families. She has stated that she has a very strong urge to become pregnant, however she is scared of the idea of us having kids together because of our backgrounds. She has stated the idea of sperm donors, however my view is I dont know how I would feel about raising another persons child especially since we havent ruled out that I can get her pregnant or not. Because if that were the case it would be different. Is she being selfish about this or are her fears justified, Because I love my love more than anything, but I dont know how to handle her idea of not having a child with me to be able to get past it.