I've never heard of Dylan as a girl's name .. !

Seems people think Sian is a male moniker.   (Sion is.)

Lyn gives some grief. Lindsay. And wasn't 'mother Walton' a Michael?

And, in North Wales, Eirian tends to be a girl's name and in the South (or at least in the West) it's a guy's.

sian (f.)