#as parent and child or as grandparent and child, including by adoption;
#as brothers or sisters, including by adoption; or,
#as half-brother brothers or half-sistersisters.
When you think about it, that's a pretty short list. First cousins, for example, can marry each other, if they don't mind the banjo music. However short the list may be, a marriage that violates this rule is void ''ab initio'', that is, the marriage is void as if it had never occurred.
===Age===
Both spouses must, in general, be over the ''age of majority'' at the time of their marriage.
Under the ''Marriage Act,'' youths ''aged 16 to 18'' can marry if they have the consent of all their guardians, or, if they have no guardians, the consent of the Public Guardian and Trustee. However, if a guardian is unreasonably withholding their consent, or can't be found to give their consent, the youth may apply to court for permission to marry.
Under While the marriages of people under the age of 16 are generally forbidden, under section 29 of the provincial ''Marriage Act'', however, a marriage the court may still be valid as long as both parties were 16 years of age or older and provided that the marriage was necessary allow such marriages if they are "expedient" and "in the best interests of both the parties.:"
Interestingly<blockquote><tt>(1) Except as provided in subsections (2) and (3), the act might be read in such a way that the marriages marriage of any person under 16 years of girls as young as 12 age must not be solemnized, and boys as young as 14a licence must not be issued.</tt></blockquote><blockquote><tt>(2) If, on application to the old common-law ages of pubertySupreme Court, might still be considered a marriage is shown to be valid. Since marriages between people this young are prohibited expedient and in Canada without a the interests of the parties, the court may, in its discretion, make an order, this rule will only apply to preserve authorizing the solemnization of and the issuing of a licence for the marriages marriage of young couples wed outside any person under 16 years of Canadaage.</tt></blockquote>
===Foreign marriages===