The SNP (for single nucleotide polymorphism), pronounced Snips, are minor variations in the genome within a population. A single nucleotide, the basic component of DNA is altered.
The SNPs are very common: there are approximately 3 million of them between two people picked at random.
These changes are usually silent or responsible for our morphological differences, although they can cause genetic diseases or predispositions to diseases.
SNPs are punctate variations in the DNA sequence. © David Hall / Licence Creative Commons