Editing Language isolate (section)

==Genetic relationships==
{{Main|Genetic relationship (linguistics)}}
A genetic relationship is when two different languages are descended from a common ancestral language.<ref name=":4">{{Cite book|last=Thomason|first=Sarah Grey|title=Language contact, creolization, and genetic linguistics|date=1988|others=Terrence Kaufman|isbn=0-520-07893-4|location=Berkeley|oclc=16525266}}</ref> This is what makes up a [[language family]], which is a set of languages for which sufficient evidence exists to demonstrate that they descend from a single ancestral language and are therefore genetically related.<ref name=":1" /> For example, [[English language|English]] is related to other [[Indo-European languages]] and [[Mandarin Chinese]] is related to other [[Sino-Tibetan languages]]. By this criterion, each language isolate constitutes a family of its own.<ref name=":4" /> This is not to be confused with family-level isolates, which are not language isolates themselves but form a primary branch of a language family, such as [[Armenian language|Armenian]] within [[Indo-European languages|Indo-European]] and [[Paiwan language|Paiwan]] within [[Austronesian languages|Austronesian]].

In some situations, a language with no ancestor can arise. This frequently happens with [[sign language]]s—most famously in the case of [[Nicaraguan Sign Language]], where deaf children with no language were placed together and developed a new language.<ref name="journals.sagepub.com">{{Cite journal|last1=Senghas|first1=Ann|last2=Coppola|first2=Marie|date=July 2001|title=Children Creating Language: How Nicaraguan Sign Language Acquired a Spatial Grammar|url=http://journals.sagepub.com/doi/10.1111/1467-9280.00359|journal=Psychological Science|language=en|volume=12|issue=4|pages=323–328|doi=10.1111/1467-9280.00359|pmid=11476100|s2cid=9978841|issn=0956-7976}}</ref>