my 5 year old wants to be a girl...

My son has been infatuated with girl things since he was about 2 & 1/2. He loves playing with girl toys, my little pony, and watching girl shows. He’s now five and a half and still very into it. He does like boy stuff also, superhero’s, etc.. but today he told us he wants to be a girl because he loves girl toys. My husband is upset. We’ll obviously love our son regardless but thinking of the struggles he’ll face in the future worries us. Is this normal five year old behavior?