My little brother and my boyfriend makes me worry?

my little brother is 14 years old, me F (20) and my boyfriend M (22)

whenever my boyfriend comes over my little brother would cling onto him, sit on his lap, cuddle with him on couch, my little brother changes the way he behaves around him and becomes so touchy

is it normal or I am overthinking

My little brother and my boyfriend makes me worry?
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