Whilst in The Woolpack on 23rd May 1995, Tina Dingle mentioned that she had a brother named Nathan. Nathan had married about six years previously and was stuck up and ashamed of his family, and they had not spoken to them since his wedding after a fight broke out.
In March 2000, at Butch's funeral, while unaware that he was the father of Cain, Zak said that Sam was his only surviving son. This hinted that Nathan had died or maybe Zak did not consider Nathan as his son any more due to Nathan shunning his working class roots.
Nathan has not been mentioned again as of 2018, although Zak had previously mentioned that he has raised six children. This could be in reference to Nathan or his half-brother Cain, although Zak's brother Shadrach raised Cain not Zak.