To protect vulnerable 16 and 17 year olds, the offences of 'abuse of a position of trust' prohibits sexual contact between adults and children under 18 in schools, colleges and residential care.
Chromosome abnormalities usually happen as a result of an error in cell division. Meiosis is the name used to describe the cell division that the egg and sperm undergo when they are developing. Normally, meiosis causes a halving of chromosome material, so that each parent gives 23 chromosomes to a pregnancy.
The result is four haploid cells. The coordination of the two meiotic chromosomal divisions gives meiosis its distinctive characteristics: a reduction in the number of chromosomes by half, accompanied by mixing of parental chromosomes, and swapping of regions between homologous chromosomes.