Which person do I have to use in this sentence?
Hello everyone,

I made up this sentence but I don't know which person I have to use.

Someone seems younger than they are.

is "they" correct?

Can I say: "Someone seems younger than it is or "Everyone seems younger than they are"?

Thanks a lot

Question

Which person do I have to use in this sentence? 
Hello everyone,

I made up this sentence but I don't know which person I have to use.

Someone seems younger than they are.

is "they" correct?

Can I say: "Someone seems younger than it is or "Everyone seems younger than they are"?

Thanks a lot

Answer

Everyone looks younger than they are. But your sentence doesn't make much sense if written out of context .