Tyra Banks' son wants to be a ''big brother''.

The 44-year-old star admitted her two-year-old boy York - who was born via surrogate after the proud mum has struggled conceiving in the past - has already hinted he wants a sibling of his own, and her mother Carolyn London thinks it's a good idea.

Speaking to 'Entertainment Tonight', she said: ''God, my mom wants more grandbabies.

''My son is rolling and running around and she's like, 'You see? He needs a friend. He's saying that these stuffed animals are his babies and he's calling himself a big brother.'

''He calls himself a big brother. I'm like there's nobody underneath you - what does that mean 'big brother?' ''

Tyra has spoken candidly in the past about the troubles she had conceiving her son, and the 'American's Next Top Model' host was undergoing vitro fertilisation treatments while filming the show in 2015.

She has also revealed she doesn't think she can conceive again, due to her previous difficulties and not having any frozen embryos remaining.

However, she has loved life has a mum and admitted this weekend that York has already becoming the ''boss'' of her household.

She added: ''I think every two-year-old has some terrible moments. And he definitely, definitely has that.

''But, he's also like in charge so when he's eating I try to tell him you must sit at the table when you eat, you cannot run around, you must sit.

''So the other day, yesterday, my mom is eating at the counter in the kitchen. He's like, 'Nana, sit down. You eating. Sit down, Nana.' ''