take an interest in someone or something 是正确的 对.感兴趣
例句:
Do you take an interest in your children?
You should take an interest in everything your child does.
have interest in 也是对的,但have an interest in更常用.因为interest当兴趣用时既有可数名词又是不可数名词.可数名词更常用
例如：I've always had an interest in astronomy.（对）
He never seems to show any interest in his children.（也是正确的）