What's it like being a grandparent in your 30s?

Matty Acton was just 18 when he started helping to raise his partner Esther's young son Ethan. Last year, when 23 year old Ethan had his own daughter, Matty became a granddad.

One of the hardest parts of grandparenting is working out how much parenting advice to offer, he tells Nine to Noon.

"You think to yourself, 'Should I tell them these things I know, or should I let them do it on their own? But other than that, it's the best."

Related stories:

Facing judgment was one of the most difficult aspects of becoming a teenage father, says Matty, who is four years younger than his partner Esther.

"We had a lot of those people saying to me when I was young, 'Why would you want to give up your life?'"

At the start of their relationship, Matty says he just wanted to build a friendship with Esther's son.

"When you're young, you're not sure how relationships are going to go, and I just wanted for him to like me."

For a long time, Ethan called him 'Matt', he says, and 'Dad' felt like a title that he had to earn.

"It doesn't really matter that much [what you're called] when you're at a point of relationship with a kid where they respect you in that way or they treat you like that."

Growing up, Ethan - who was 12 when his little brother Xander was born - was always a very kind and loyal boy, Matty says.

Ethan proposed to his now-wife Maddie just six months after they got together, and not long after their wedding, she gave birth to their baby girl Illyria.

He's now a really hands-on dad, Matty says.

"It does make you quite proud to see your son take on that role really easily".

When Matty and Esther first found out they were becoming grandparents, the couple were "really ecstatic", he says, and their younger kids - eight-year-old Eden and 11-year-old Xander - were excited, as well.

"Everyone always thinks, "Oh, you know, the kids will grow up, and away they go. But then grandchildren come, and your whole family dynamic changes again."

Matty and Esther - who host the podcast UnderagedGrandparents-haven't quite "crossed over" into viewing themselves as grandparents, he says, and still feel mostly like parents.

In sketches about family life on social media, Matty doesn't shy away from the realities of it, like how it's "absolutely joyous" to see his kids come home from school, but also to see them head off in the morning.

"They're the main things that people cast judgment about [on social media], not so much about having kids young, surprisingly, because I really thought people would have more to say about it."

Matty's impersonations of family members are what attract the most comments on social media, he says. From followers around the world, he's learned that children everywhere all do the same things.

"Shoes are always off, hats are always gone. And if something breaks, it's never their fault - never, ever …. I don't know why my son will only use the toilet at home."

We have to laugh about the foibles of family relationships, Matty says, or they get even more intense.

"Everyone is just like going through life, trying to do their best, right? No one's perfect, and that's totally fine."

Making fun of his own mistakes is good fodder for silly videos, too.

"They always say when your partner leaves, the things that annoy you the most are the things that you'll probably miss. They're the sorts of things that I look out for in my relationship to make sketches on."

11-year-old Zander is "taking it pretty well" that, thanks to their mums, his classmates now sometimes see Matty's social media videos.

"He's only about a dirt bike at the moment. Yesterday, he spent most of the afternoon finding things in his bedroom that he wanted me to put on Facebook Marketplace so he could buy himself a motorbike.

"Now he's trying to say that I have to pay him for every video so he can buy a dirt bike."