My younger brother died from ALL when he was 24, got it at 22. Although he was in his twenties, this was considered the "childhood" form of leukemia. Of course

My younger brother died from ALL when he was 24, got it at 22. Although he was in his twenties, this was considered the "childhood" form of leukemia. Of course this is anecdotal, but because of my experience as the surviving eldest child, I happen to agree with you. But it's also entirely possible that he had less exposures than I did early in life, despite being the younger. Just one example off the top of my head, he was brought home after delivery to a different house than I was, a new construction at the time. I could also envision some repeat parents "learning" from their experiences with the first child such that the first child actually has more exposure. I do not particularly want to discuss this with my parents to determine if they could think of a reasoning though, lest I add to their survivor's guilt.