Hoping not to sound too scientific, but a well known and one of the first studies in epigenetics (from mid 1940s), found that people whose mothers were pregnant with them during a famine were more likely to develop certain diseases such as heart disease, schizophrenia, and type 2 diabetes.
On that basis she may have possibly caused B to have poor health in later life by underfeeding herself during pregnancy.
On that basis she may have possibly caused B to have poor health in later life by underfeeding herself during pregnancy.