SOLVED. A book about girl whose twin is a seventh son of a seventh son [s]

[Lindsey]

I can remember much so sorry :-)
The girl is the 15 child (if I remember correctly)
Her family called her the cursed child because being the 15 child is considered unlucky.
Her father is a college teacher of the family soon moves towns to a city that is protected by a magic border too keep the magic creachers of the beyond out.
Her brother is the seventh so of a seventh son so has great magic abilities.
I guess that's a little more info than I thought.
The book is fantasy.

[Kit★]

Kinda sounds like Thirteenth Child

[bookel]

Could it be
Seven Daughters and
Seven Sons by Barbara Cohen?

[Lou]

everything except the 15th child bit fits with Thirteenth Child, so I second it.

[Julie]

From the description, this DEFINITELY sounds like Thirteenth Child.

[Lee Anne]

Agreed--Thirteenth Child--which is followed by Across the Great Barrier and The Far West

[Lindsey]

YES thank guys you were a big help:-)