Paul Langer's daughter

Paul Langer's child was the unborn child of Paul Langer and Melba. Clyde Langer was its half-brother (and first cousin).

When Melba became pregnant in 2009, Paul ran off and returned to his son Clyde. He kept a photo of his unborn child in his pocket and showed it to Clyde. Clyde convinced Paul to return to Mel and to be a good father to his child. (TV: The Mark of the Berserker)

The child may have been a girl, since Clyde later claimed he'd "looked after [his] little cousin a few times, not that she's an alien". (TV: Sky)