I love my MIL, I really do. But since my DS was born (he's 4.5) she has been going on, and on, and on, about him staying at her house by himself. My PIL live 2.5 hours away, so it would mean driving up and leaving him there, and then coming back and picking him up - 10 hours in total.
But honestly, it's not that. In my heart, i think - NO NO NO. He's only 4.5, only a baby really 
, and although he's very close to my MIL I think he'd really miss us. I'd worry.
So AIBU? How old were your DCs when they first started staying alone at the GPs??