Morality of the procedure aside, this is a very low quality study.

The most glaring omission is that they didnt account for possible confounding due to religious/political beliefs. To be fair, they acknowledge that this is a limitation, but I'd bet that this is possibly the main driving factor behind any differences in personality between the two groups.

We know for a fact that religious/conservative populations are markedly different across a variety of character traits, and they are also significantly likely to circumcise their child.

Any study that doesnt account for this is invalid IMO.