The idea that Jamie (mistakenly displayed as "Jaime" on the main page) might be a Changeling despite the fact that Changelings are a now-bypassed evolutionary transition is no more credible than the idea that there are exceptions to the rule that mutants' powers manifest at puberty - especially since the term "mutant" has, for some time, represented the evolutionary steps presented in offspring versus parent. Was every such step only verifiable at puberty? Mm... If mutations themselves are all about survival (a philosophical concept more than an evolutionary one, IMO, but one which seems to be shared by Marvel's general and PAD's particular evolutionary constructs) then it makes less sense for them to fail to manifest until puberty. After all, a child who makes to puberty likely has less need for an adaptive trait. If the traits are meant to increase the chances of survival, then being present at-birth is a must.