Not To Be Confused With
Origins can be worth knowing, but they don't settle truth. The genetic fallacy is close to ad hominem, but it targets the SOURCE of an idea rather than the person stating it.
“That belief comes from paganism, so it's false” — or “from the Bible, so it's true” — both reason from pedigree instead of evidence. A practice's origin (say, a symbol with pre-Christian roots) does not by itself decide whether the Church was right to adopt or reject it.
Examples
- “Christmas has pagan roots, therefore Christians shouldn't celebrate it” — origin treated as a verdict.