I cannot comment on the multiple sibling point, but I will concur wholeheartedly with the screen time observation.

DD has NEVER been a child who self-regulates screen time very well, and her behavior is also inversely proportional to the amount of such time spent with electronics.

Physical activity and meeting someone ELSE's schedule points really help her. She also voluntarily does a lot of other things all on her own as long as we limit that screen time. Always has. smile

Schrödinger's cat walks into a bar. And doesn't.