My younger child (3y4m) was diagnosed with retained reflexes at one point. He also has benign hypotonia that has improved greatly, but is still present. He was also diagnosed with failure to thrive as an infant, with very low oral motor tone that contributed to nursing issues. He actually still has head lag, something that should disappear in infancy.

They were really freaked about him when he was tiny--we had an MRI, tests for muscular dystrophy, CP was considered...but he seems to be fine now. In fact, he appears far more neurotypical than his sister, who has looked SPD-ish, ASD-ish, and ADHD-ish in her time, and has met all his milestones and then some despite a slow start (didn't sit alone till 9 months or crawl till 11 months; we had him in PT till age 1ish).

I don't know what the deal is with these odd signs of his and I suspect we never will, though there is a family history of "floppiness." I do notice that there seems to be a strangely high # of gifted kids with hypotonia.