Relatedness between a pair of family members

Source: R/Covariance_matrix_functions.R

get_relatedness returns the relatedness times the liability-scale heritability for a pair of family members

get_relatedness(s1, s2, h2 = 0.5, from_covmat = FALSE)

Arguments

s1, s2

Strings representing the two family members. The strings must be chosen from the following list of strings:

  • g (Genetic component of full liability)

  • o (Full liability)

  • m (Mother)

  • f (Father)

  • c[0-9]*.[0-9]* (Children)

  • mgm (Maternal grandmother)

  • mgf (Maternal grandfather)

  • pgm (Paternal grandmother)

  • pgf (Paternal grandfather)

  • s[0-9]* (Full siblings)

  • mhs[0-9]* (Half-siblings - maternal side)

  • phs[0-9]* (Half-siblings - paternal side)

  • mau[0-9]* (Aunts/Uncles - maternal side)

  • pau[0-9]* (Aunts/Uncles - paternal side).

h2

A number representing the squared heritability on liability scale. Must be non-negative and at most 1. Defaults to 0.5

from_covmat

logical variable. Only used internally. allows for skip of negative check.

Value

If both s1 and s2 are strings chosen from the mentioned list of strings and h2 is a number satisfying \(0 \leq h2 \leq 1\), then the output will be a number that equals the percentage of shared DNA between s1 and s2 times the squared heritability h2.

Details

This function can be used to get the percentage of shared DNA times the liability-scale heritability \(h^2\) for two family members.

Note

If you are only interested in the percentage of shared DNA, set h2 = 1.

Examples

get_relatedness("g","o")
#> [1] 0.5
get_relatedness("g","f", h2 = 1)
#> [1] 0.5
get_relatedness("o","s", h2 = 0.3)
#> [1] 0.15


if (FALSE) {
# This will result in errors:
get_relatedness("a","b")
get_relatedness(m, mhs)
}