GCSEs or Standard grades including english, maths and preferably double science. However, whatever your future plans, it's best to keep your options open and choose 2 sciences, as choosing only one can limit your opportunities.
Science based 'A' levels or Highers such as biology and chemistry with physics or maths. Alternatively other qualifications such as HNDs, GSVQs, advanced GNVQs may be accepted as an alternative depending on the institution.
A university degree such as genetics or a more general course which includes genetics such as biology, applied biology or biochemistry. Many of the genetics degree courses are combined with another subject such as 'genetics and microbiology', or 'genetics and forensic science', or offer degrees that include an industrial placement. Information about the each degree and entrance requirements can be obtained by consulting individual university's prospectuses or their websites. There are currently 115 genetics courses offered around the U.K. For more information and to find out entrance requirements visit Universities and Colleges Admissions Service for the UK (UCAS) (http://www.ucas.com).
The majority of researcher positions also require a post graduate qualification (e.g. MSc or PhD). Some non-graduate positions are however possible through Modern Apprenticeships which are offered to those aged over sixteen and combine paid employment with training for technician posts.
For more information on careers and qualifications, your choices and options talk to your careers teacher at school and your careers advisor from the local career development centre.
Other pages in the Education section that you may be interested in: