TABLE 1.

Heterogeneous stock mouse pedigrees

Pedigree	Pedigree class	No. of nonoverlapping sibships in the pedigree	No. of retained sibships	No. of meioses
1	Multigenerational	17	17	464
2	Multigenerational	27	20	728
3	Multigenerational	23	19	602
4	Multigenerational	14	9	254
5	Multigenerational	11	9	242
6	Multigenerational	5	3	68
7	Multigenerational	4	3	100
8	Multigenerational	2	1	16
9	Sibshipa	2	1	20
32–85	Sibship		51	1146
Total		180	132	3640

^aThis family was composed of two sibships sharing a common mother but with different fathers.