Both genetics and environment have been implicated in influencing pro-social or altruistic behavior.<ref>{{cite book | url=https://books.google.com/books?hl=en&lr=&id=fM7RAgAAQBAJ | title=Prosocial Development: A Multidimensional Approach | isbn=978-0-19-996478-9 | last1=Padilla-Walker | first1=Laura M. | last2=Carlo | first2=Gustavo | date=15 December 2015 | publisher=Oxford University Press }}</ref> Candidate genes include OXTR ([[gene polymorphism|polymorphism]]s in the [[oxytocin receptor]])<ref>https://psycnet.apa.org/fulltext/2008-17541-005.pdf</ref><ref>{{cite journal | url=https://www.sciencedirect.com/science/article/abs/pii/S0306453012000546 | doi=10.1016/j.psyneuen.2012.02.001 | pmid=22377540 | title=Oxytocin, but not vasopressin, increases both parochial and universal altruism | date=2012 | last1=Israel | first1=Salomon | last2=Weisel | first2=Ori | last3=Ebstein | first3=Richard P. | last4=Bornstein | first4=Gary | journal=Psychoneuroendocrinology | volume=37 | issue=8 | pages=1341–1344 }}</ref><ref>https://www.sciencedirect.com/science/article/abs/pii/S0018506X1100105X</ref>, [[CD38]], [[COMT]], [[DRD4]], [[DRD5]], [[IGF2]], [[AVPR1A]]<ref>https://journals.plos.org/plosone/article?id{{cite journal | doi=10.1371/journal.pone.0025274 | doi-access=free | title=AVPR1A Variant Associated with Preschoolers' Lower Altruistic Behavior | date=2011 | last1=Avinun | first1=Reut | last2=Israel | first2=Salomon | last3=Shalev | first3=Idan | last4=Gritsenko | first4=Inga | last5=Bornstein | first5=Gary | last6=Ebstein | first6=Richard P. | last7=Knafo | first7=Ariel | journal=PLOS ONE | volume=6 | issue=9 | pages=e25274 | pmid=21980412 | pmc=3182215 | bibcode=2011PLoSO...625274A }}</ref> and [[GABRB2]].<ref>{{cite journal| pmc=3871336 | pmid=24132092 | doi=10.1098/rsbl.2013.0395 | volume=9 | issue=6 | title=Genes underlying altruism | year=2013 | journal=Biol Lett | page=20130395 | last1 = Thompson | first1 = GJ | last2 = Hurd | first2 = PL | last3 = Crespi | first3 = BJ}}</ref> It is theorized that some of these genes influence altruistic behavior by modulating levels of neurotransmitters such as [[serotonin]] and [[dopamine]].
===Sociology===
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* Norms
In 1970, Schwartz hypothesised that extreme altruism is positively related to a person’s moral norms and is not influenced by the cost associated with the action.<ref name=":3">{{Cite journal |last=Rusch |first=Hannes |date=2022 |title=Heroic behavior: A review of the literature on high-stakes altruism in the wild |url=https://linkinghub.elsevier.com/retrieve/pii/S2352250X21001330 |journal=Current Opinion in Psychology |language=en |volume=43 |pages=238–243 |doi=10.1016/j.copsyc.2021.07.024|pmid=34454246 |doi-access=free }}</ref> This hypothesis was supported in the same study examining bone marrow donors. Schwartz discovered that individuals with strong personal norms and those who attribute more responsibility to themselves are more inclined to participate in bone marrow donation.<ref name=":3" /> Similar findings were observed in a 1986 study by Piliavin and Libby focusing on blood donors.<ref name=":8" /> These studies suggest that personal norms lead to the activation of moral norms, leading individuals to feel compelled to help others.<ref name=":3" />