Beyoncé and Jay Z's twins are ''very different''.

The couple welcomed daughter Rumi and son Sir into the world in June and their proud grandmother, Tina Knowles Lawson, adores being around the ''cute'' youngsters.

Tina - who is Beyonce's mother - said: ''They're doing great. They are absolutely beautiful and so much fun. I mean, I haven't ever been around twins, but it's so cute, I can hardly take it.

''Yes, [it's crazy]...it's just really, really different with two babies. I mean, a boy and a girl. Very different personalities.''

Beyoncé, 36, and 47-year-old Jay are also parents to five-year-old Blue Ivy and their older girl is already a ''good sister'' to her twin siblings.

Tina said: ''She's a good sister.''

Her husband, Richard Lawson, added to 'Entertainment Tonight': ''Just seeing her grow up, it's bringing some maturity. She's only five, but you can see the transition in terms of her being a little more calm. Because she's the diva, but she's sharing her diva-dom.''

Meanwhile, Tina bonds with her son-in-law over their shared passion for art.

She said of the '99 Problems' rapper: ''We have a great passion for art and we talk about it all the time and he shows me new artists and sometimes I show him new artists. He has a great eye.''

It was previously reported that the 'Formation' hitmaker had initially been worried Blue Ivy would ''feel left out'' once the twins arrived, but was pleased when she proved to be an ''amazing'' big sister.

A source said: ''Beyoncé has been very busy with the newborns, but she's also been able to relax a bit. It's helped her that Blue has been such an amazing big sister.

''There was no need to worry because Blue is great. She takes her job as a big sister very seriously and helps out a lot.''