If you know the first number, a, and the common difference d, (where d is negative), then the nth term is a + (n - 1) * d: exactly the same as in
an increasing linear sequence.
Epigenetics provides another way of understanding how genes and environment interact in that there is
increasing evidence that gene expression is moderated by the environment in which the organism grows and develops.15 Genetic information is encoded not just in DNA
linear sequences but in epigenetic changes in chromatin structure such as DNA methylation or covalent modifications of the DNA - binding proteins.