Figure 3. Intergenerational and transgenerational inheritance.

Maternal exposure to a poor environment exposes both her developing fetus in utero (F1, orange) as well as the developing germ cells in the fetus which later give rise to F2 (yellow), both of which are present at the time of environmental exposure (referred to as inter-generational inheritance). However, the cells which form the F3 generation (green) are not present at the time of environmental exposure; if they carry phenotypes, they do so by transgenerational inheritance. For paternal exposure to poor environment, only the sperm cells which form the F1 generation are present and directly exposed to the poor environment (intergenerational inheritance), whereas phenotypes which persist into F2 and beyond are referred to as transgenerational inheritance.