At what age would you leave children at home by themselves all day? I'm asking as I noticed a 12yo boy out alone on his bike at 7.30am this morning and he was still out alone at 6pm tonight. I'm off work today and been in and out with my 2 much younger children which is why I've seen him out in his bike for most of the day alone. Both his parents are doctors and only moved to the area about 4 weeks ago. At that age my parents left me inside with my sister all day but with strict instructions not to go outside (30 years ago and a different county). Is 12 old enough? I have no idea but this boy looked so alone and waved every time we saw him, like he was looking for company. Are 12yo's more streetwise now than I was 30 years ago?