Mapacha au ndugu pacha ni watu au wanyama waliozaliwa kwa pamoja kutoka tumboni mwa mama yao[1]. Kwa binadamu mara nyingi huwa wawili.
Kuna aina kuu mbili za mapacha ambao ni wale wanaofanana na wale wasiofanana. Tofauti ni kwamba wa kwanza wametokana na kijiyai kimoja kilichofikiwa na mbegu moja, kumbe wa pili wametokana na vijiyai viwili vilivyofikiwa na mbegu mbili. Hivyo wa kwanza wana jinsia ileile na kwa kawaida kabisa DNA ileile, kumbe wa pili DNA zao ni tofauti, ila zinafanana kiasi kama zile za ndugu wote wenye baba mmoja na mama mmoja[2].
Kimataifa aina ya kwanza inatokea mara 3 katika ujauzito wa wanawake 1,000[3].
Bacon, Kate. Twins in Society: Parents, Bodies, Space, and Talk (Palgrave Macmillan; 2010) 221 pages; explores the experience of child twins, adult twins, and parents of twins, with a focus on Britain.
Wenk RE, Houtz T, Brooks M, Chiafari FA (1992). "How frequent is heteropaternal superfecundation?". Acta geneticae medicae et gemellologiae. 41 (1): 43–7. PMID 1488855.
Girela, Eloy; Lorente, Jose A.; Alvarez, J. Carlos; Rodrigo, Maria D.; Lorente, Miguel; na wenz. (1997). "Indisputable double paternity in dizygous twins". Fertility and Sterility. 67 (6): 1159–61. doi:10.1016/S0015-0282(97)81456-2. PMID 9176461.
Am J Med Genet C Semin Med Genet. 2009 May 15;151C(2):136-41. Not really identical: epigenetic differences in monozygotic twins and implications for twin studies in psychiatry. Haque FN, Gottesman II, Wong AH.
Makala hii kuhusu mambo ya biolojia bado ni mbegu. Je, unajua kitu kuhusu Mapacha kama historia yake au mahusiano yake na mada nyingine? Labda unaona habari katika Wikipedia ya Kiingereza au lugha nyingine zinazofaa kutafsiriwa? Basi unaweza kuisaidia Wikipedia kwa kuihariri na kuongeza habari.