I was breastfed at the beginning . . . but when I was about 3 months old, there was a stretch of time where I had to be given many bottles over a period of a couple of weeks. After that, textbook nipple preference--went on a nursing strike and wouldn't have anything to do with the breast. Mom has always expressed regret that she didn't get to nurse me for longer. Little brother was BF for awhile, but also went to bottles fairly quickly--and had serious allergies/lactose intolerance, so was put on soy.
DH was breastfed for all of a couple of weeks, but because of the pain involved (we now know that he was/is tongue-tied, which was the likely cause of MIL's pain), he was switched to formula.
My mom is a big fan of breastfeeding and I am expecting no challenges from her on nursing this baby-to-be . . . MIL has, I think, convinced her that breastfeeding "just wouldn't work" for her (same thing with birth, actually), and may need some educating. But she knows not to mess with me on natural pregnancy/childbirth issues--she has known me since I was 14, and I have been planning on becoming a midwife for several years BEFORE that, so she is pretty comfortable with my crunchiness.
Interestingly, neither DH or I have any major health issues as a result of the FF--although DH has developed some weird unknown allergies in the last few years.
FIL, though . . . was born in a displaced person's camp in Germany, and his mother was told to give him bottles of powdered milk!
When he developed diarrhea (I'm doubting that the water there was particularly clean/healthy) and got very, very sick from dehydration . . . the doctor at the camp put him on BUTTERMILK to get some weight back on him. FIL's mother is convinced, to this day, that the buttermilk saved his life . . . but FIL has TERRIBLE allergies to many, many things; wouldn't surprise me if it was due to the very early exposure to dairy.