Here we show that fathers exhibit more affection and attachment and fewer ignoring behaviors toward children whose smell they can identify than toward those whose smell they cannot recognize. Thus, olfaction might serve as a means for males to determine their genetic relatedness to purported offspring. We also demonstrate that mothers’ olfactory recognition and hedonistic ratings are linked with the use of physical punishment. Mothers report using more punishment with children whose odor they cannot recognize and less with children whose odor they rated as more pleasant.
— From A Preliminary Investigation of Parent–Progeny Olfactory Recognition and Parental Investment, originally published in Human Nature, with thanks to Jan for the link!