Unlike natural selection, genetic drift does not depend on an allele's beneficial or harmful effects. Instead, drift changes allele frequencies purely by chance, as random subsets of individuals (and the gametes of those individuals) are sampled to produce the next generation.
Answer:
On the basis of gender preference.
Explanation:
In the modern view of adaptation, the main cause of infanticide is not the food but the gender preference. In many societies, people killed their infant when they knew that the infant is a girl. They thought that having a girl is curse or shameful thing so they kill the infant. These type of people wants male baby or prefer male child so that's why they kill the infants. In the ancient times, infants were killed that were abnormal or having any defects but today it happen due to gender preference.