Legislation regarding sexual offences in the United Kingdom is devolved. Sex with an adult who is related as parent (including adoptive parent), grandparent, child (including adopted child), grandchild, brother, sister, half-brother, half-sister, uncle, aunt, nephew or niece, is illegal. In England and Wales the offence is against the Sexual Offences Act 2003 which effectively replaced the offence of incest with two new wider groups of offences: familial child sex offences (sections 25--29) and sex with an adult relative (sections 64--65). These laws are intended to protect the rights of people, so as to avoid potential violation. However, these laws still outlaw consensual sexual relationships between family members, even if they are fully willing and knowledgeable to the potential consequences. There has been some debate surrounding the rhetoric used by the Sexual Offences Review Team. Roffee discusses how the language used manipulates the reader to deem consensual familial sexual acts as illegal to the point of immoral. In Northern Ireland similar offences are against the Sexual Offences (Northern Ireland) Order 2008.

What's the best answer to this question: can you marry your sister in the uk?
no