Is it normal for a 11 year old boy fight to change his cousin's diaper?

Is that a normal behavior or rather something else, his behavior would include pushing the mother away or hit her hand so he could change the baby girl diaper. I mean who would want to change a loaded diaper of poo with the smell and everything? Did he think about how would she feel when she's grown up and learn that?
Is it normal for a 11 year old boy fight to change his cousin's diaper?
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