This 2012 Patheos article claims Section 16 of Alberta's 2012 education act it forces parents not to teach that homosexuality is a sin as part of their official schooling, but I can't confirm it.
The claim on patheos.com has quite a bit of hyperbole.
The Province of Alberta's 2012 Education Act can be found here. The relevant portion (Section 16) states
Diversity and respect
All courses or programs of study and instructional materials used in a school must reflect the diverse nature and heritage of society in Alberta, promote understanding and respect for others and honour and respect the common values and beliefs of Albertans.
For greater certainty, the courses or programs of study and instructional materials referred to in subsection (1) must not promote or foster doctrines of racial or ethnic superiority or persecution, social change through violent action or disobedience of laws.
Note that this only requires that the instructional materials do not promote various viewpoints that could be construed as hatred (racial or ethnic superiority) and must be respectful of others. It also only applies to instructional materials. This does not prevent parents from imprinting their own personal views.
The concern shown on patheos.com seems to be about homeschooling students. However, even if students that were home-schooled were exposed to viewpoints that violated section 16, it would be impossible to determine if it was as part of their formal education or as part of family time.