Kate Hudson finds monogamy difficult because she is "ruled" by her "sexual energy".

The 29-year-old actress ? who has a four-year-old son Ryder with ex-husband Chris Robinson ? said she struggles to understand the concept of staying faithful.

Hudson said: "I got into this very controversial discussion once. I was married at the time and I was asked: 'Do you think monogamy is possible?' And I said: 'No, I don't think we are made to be monogamous, we are animals.'

"If you have that personality, it's never going to go away because you are ruled by your sexual energy."

Although Hudson is sceptical about the success of long-term commitment to one person, she confusingly says she could never be in an open relationship.

Hudson told The Sunday Times magazine: "I would be doing myself a disservice by saying monogamy is going to be easy. That said, I could never be in a relationship that wasn't monogamous because I couldn't deal with it.

"You have to remember not hurting people comes first."