At just 18 months old, young children can show biological evidence of added stress.
https://www.scientificamerican.com/article/when-a-mom-feels-depressed-her-babys-cells-might-feel-it-too/
origin - https://www.pipiscrew.com/?p=16525 when-a-mom-feels-depressed-her-babys-cells-might-feel-it-too