Interesting topic!
We have a DS2.5 and somehow I expect him to be gifted as well, but I do think that DD5,5 is the smarter one. For example, DD was mega alert since birth, while DS alertness started when he was a few months old.
And and 2.2 DD was making remarks about 'real' cats or horses, while DS is still trying to put sentences together.
So, is he less gifted or a late bloomer?

In my family, both my sis and me are consider intelligent (but not gifted), but my younger sister is the one considered the super-smart one by my parents.