Pop singer Lily Allen is quite sure that actor and comedian Keith Allen is her father, but has no clue how many siblings she has.
"I don't know. I honestly don't. My dad lies about it. He's like, 'Okay, it's eight.' And I'm like, 'We know it's twelve.' There are a few years before he met my mom that are unaccounted for, but law of averages would say he had five [kids then]." [Link]
