Tom Hanks' grandchildren ''don't care'' about his fame.

The 62-year-old actor is a Hollywood icon, but his fame is lost on his two granddaughters Olivia, eight, and Charlotte, five, who ''don't care'' about his success, or the success of their father Colin Hanks.

Colin - who has his tots with wife Samantha Bryant - said: ''They don't care about him at all. Children are great humblers. They don't care what you do [or] ... what you have done. They just want to do their kid stuff.''

The 'Life in Pieces' actor, 41, also revealed Tom acts just like ''every other'' grandparent when he's around his family, including giving the girls treats they ''shouldn't be having''.

Speaking to Us Weekly magazine, Colin added: ''[The time they spend with Tom is] like every other playdate with a grandparent. The grandparent gives them stuff they shouldn't be having, and the grandparents don't listen to what the parents are saying they should be doing.''

Meanwhile, the 'Toy Story 4' actor - who is also grandparent to his son Chet's daughter - previously insisted he and his wife Rita are ''the most cool'' grandparents.

He said: ''When you have grandkids, if you're with one of them - or all three of them - look, there's no book, no radio, no TV. You're going to be entertained by them every moment that you're there. Sit back and watch the show!''

Whilst Rita added: ''We're the cool grandparents.''

To which Tom replied: ''I think [we're] the most cool.''

The 'Sully' star is father to Colin and Elizabeth with his late ex-wife Samantha Lewes, as well as Chet and Truman, whom he has with his wife Rita.