I grew up in a household with no men in it for as long as my memory goes back, and I worried about having boys because I thought I wouldn't understand them - and a lot of the time I don't! But I don't miss this apparent 'bond' that women say they have with daughters (sorry MrsD, obviously I know you do, and it's a bit different in your situation) but all I can say is that being the mother of three boys fascinates me and worries me!
The other thing I will say is that because my children are all of the same gender, and all a different gender to me, I don't put any of dynamics of the individual relationships (either between me and them, between the boys themselves, or between them and my DH) down to 'understanding one another' or 'not understanding one another' due to gender differences iyswim. It can be a lazy assumption.
I go through phases of (not favouritism exactly, but) bonding and getting along with different sons best at different times in their lives, and they do that with one another too. The dynamic is always changing.
For example I am having a very challenging time with my DS2 at the moment, and a very easy time with DS1, though for the first 10 years DS2 was a dream to parent because he was so open and straightforward and easy to understandand, whereas DS1 has always been the deep and moody type. But DS2 is 16 now and has developed traits, interests and a personal ethos that leave me bewildered, and I know it is because because of fundamental differences in the way we are. I just don't understand him, or 'get' why he want to be the person he clearly wants to be.
Whereas, although DS1 is sometimes too guarded and private and complex, I totally understand him and feel comfortable with the person he is.
If DS2 were my only boy I might be in danger of saying 'I just don't understand boys.' As it is, I just don't understand him.
I could sit here all day listing my 3 children's differing characteristics, and if one or other of them were a girl it would be so tempting to assume that that was how girls were, because as a woman it was a trait I identified with.