[Vocabulary] .......yours?

[englishhobby]

Could someone help me understand what the man asks the woman (she is a robot according to the plot):
https://youtu.be/RPdbetwOXmM?t=280

Logically, he asks something like 'Is it the father of yours?', because she answers "Please, grandfather at least'. But I can't distinguish the words he says.

 

[Roman55]

I hear:

'Brother of yours?'
'Please, grandfather at best.'