[Fairview]

All kidding aside, that does look like a chick on Jesus’s right.

[Lee'sGhost]

I’ve always thought that, even as a little kid.

[Bob J]

DaVinci often painted male figures with feminine features. It was his attempt to convey youth.

Nothing strange here.

[FreedomCalls]

All kidding aside, that does look like a chick on Jesus’s right.

It's St. John (as in Matthew, Mark, Luke, and John). He was the youngest of the disciples. He has always been depicted as young and indeed, somewhat feminine as shown in all these paintings of him.