This is psychology/sociology, not MINT. If you start to question whether childhood experience is a valid causal vector to influence adult behaviour you should become a philosopher while the rest of the world happily assumes causation.
Also if you had actually glanced at the study you’d have seen that it’s a systematic review. Skimming over it what it’s saying is “there’s a ton of unorganised data out there that nonetheless shows a clear and distinct pattern we should study the topic for its own sake”.