Maybe it's more prosaic than what you expected (I did), but it's there:

> Haworth's drinking water, they believe, came from springs which were contaminated by rainwater that had soaked through the church graveyard - which was close to the parsonage where the Brontes lived. Long-term exposure to the bacterial infections this caused could have weakened the constitutions of the siblings and those of their neighbours, whose average lifespan was only around 26.

Yes it does! It’s because their water was polluted by the close proximity of the graveyard.

Because their water source was contaminated by rainwater that ran through a graveyard. I don't know if that's a plausible claim, but that's the claim.