When I figured out I was trans, I was comforted by the fact that a good friend of mine is the daughter of a transwoman, and is a wonderful, kind, happy, and relatively well-adjusted (compared to whom I tend to spend time with) person. I have little worry about how my own daughter (18 mos) will grow up, because I will make an effort to put many adult role models into her life, and make sure she feels loved and accepted for who SHE is. Young children are kind of narcissistic by nature.
Here are the things my friend told me, and even though these are only the experiences of one family, I hope you all find this helpful.
1. When my friend's dad transitioned, she told her children that she loved them very much and was proud to be their father, but was really a woman and was going to begin living as one. I think the kids were about grade-school age. I haven't thought about what I'm going to do, but I will need to make it a point that women don't normally "grow" into men like mommy, especially since she herself is female.
2. My friend still calls her dad her "dad" even in public. I'm female and would still want my daughter to call me "mom". I gave birth to her and I'm proud of that. I was worried how this would look in public, but my friend assured me that transitioning in itself takes so much courage and willpower, that hopefully I'd be proud enough of my family and my body that I didn't care what strangers thought.
3. I can't speak for myself yet, but as for my friend, she grew up to be a wonderful person. She's married, child-free, happy, and isn't without problems but gets through them alright. She participates in her dad's pride parade float every year, and is clearly on good terms with / loves both of her parents. She did admit to me that it was weird having a transgender family member, but she grew up with people who were supportive of her dad's decision, and supportive of trans issues in general. Her parents were already divorced for non-gender issues before the transition.
I feel weird speaking for my friend for point 3, but I hope the other stuff I passed on is helpful.