Agree totally with you, Shootingstar. I had no "transition" to parenting because of all of my sitting experience, starting with my brother and continuing through college, when I was a mother's helper after class.
My younger son really put himself in a position to get babysitting jobs; he was a teacher assistant at our synagogue preschool, once a month program, where the parents stay with the kids, for 2 years and then he was an assistant in the Hebrew School kindergarten class for 2 years, until his racing schedule precluded him working on Sundays.He also took child development in HS, where they had a preschool on campus. He was the only boy in the program. The first family he sat for (he was in 8th grade) had a 4 month old, a 4 year old and a 8 year old. He changed diapers from the beginning. And this is the one who is the big, tough Marine, now! He still relates stories of how some of his co-workers don't have a clue about child rearing, as occasionally he and his wife will babysit for another couple. I essentially got the older one his first babysitting job, and he also worked for them for years, after the couple got divorced, etc. The oldest one of those kids is now at the same university my son went to! I remember the first time he sat for them, the kids were so wild, one knocked over a lamp and Josh called me, frantically worried about what the parents would think. They didn't care at all and it seemed "normal" to them. He knew that if he and his brother had done that, we would have been pissed if they acted that way with a sitter. But, they calmed down, eventually, and my son became a part of that family for a time.