I would say the seeds of becoming nudist were certainly there as a child, although I wasn't brought up nudist as such. Being naked just happened to be an incidental thing which no one ever thought anything of. Sharing baths with friends and relatives, school showers, getting changed in front of other people, people sleeping naked, and knowing about nude swimming were all normal things. Likewise, magazines with centrefolds were never hidden. It was the same situation with some of my friends. In short, the naked body was nothing to be embarrassed or uncomfortable about. It was due to other things going on in life that I just didn't really get into outdoor nudity until my 20's.
Among my mother's pictures are several that show me nude as a child in our backyard, in the sprinkler, in a galvanized wash tub, running, etc, so I got an early start on the joys of no clothing. As I grew in a small farming community my cousins and I often played nude in the woods and swam nude together in the local river. It seems like boys and girls both started wearing swim suits about he age of 12-14 but all that early nudity stuck with me and I have taken advantage of every opportunity since to go clothes free.
I think the greatest advantage of growing up this way was learning early that boys and girls look different without clothes and accepting that as a natural thing rather than something to be amazed at. It didn't matter back then and still doesn't today. I just enjoy being nude and don't care if I am seen by men, women, children or whether those seeing me are clothed or nude.