Simon Cowell wants to start a family, but only if he can stay faithful.The music mogul has admitted he doesn't know if he'd be a good father "for the first six months" but he would do well providing he didn't cheat on the mother.He told the Sunday Mirror newspaper: "Would I like kids? If I knew I could be, and how could I put this delicately, faithful, then yes. I do like kids."I'm not sure I would be a good dad for the first six months or so but once they know who I am, I would like it. I definitely haven't ruled out having children."The 53-year-old star - who revealed he wants a daughter - also refused to "completely rule out" adoption but explained he'd rather start his own family.He said: "I think I'd rather have my own but then again I wouldn't completely rule out adopting either."If I did have a child, I have to say I'd prefer a girl."And according to The Sun on Sunday newspaper, his fellow 'Britain's Got Talent' judge Amanda Holden has said he will be a "fun" father, even if he couldn't deal with every aspect of parenthood.She added: "He is so good with children. I want him to have children because he would genuinely be a fantastic dad because he is good fun."But there is no way he would go near a nappy or a poo or anything like that. When the baby's walking and could, have a conversation with him and know who he is, that would be fine."