"Have sisters made a pact to deceive me?"

Which sister's the mum?

I don't know which of two women is my child's biological mother.

Last summer I had a brief holiday romance with a girl called Rose and on the last night I got horribly drunk and accidentally slept with her sister, Holly.

I didn't hear from either of them for a year and then out of the blue, Holly called me and told me that she'd given birth to my child. I immediately went to Manchester to see them.

The thing is, I'm starting to suspect that the baby is Rose's. I found out that she has been in a serious relationship for three years and plans to go to university in September, whereas Holly is going nowhere and desperately wants a family and a man in her life.

What do you think I should do?