Adult 1 Birth Order 1 Birth order Competitive Behavior 1 Ethiopia 1 Family Relations 1 Farmers 1 Humans 1 Inequalities 1 Kin selection 1 Psychological Theory 1 Psychosocial Support Systems 1 Reciprocity 1 Sibling Relations 1 Social capital 1 Support network 1 adult 1 agricultural worker 1 article 1 birth order 1 competition 1 competitive behavior 1 ethnology 1 family relation 1 government 1 human 1 human experiment 1 inheritance 1 investment 1 kin selection 1