Russian President Vladimir Putin wants marriage to be defined as the union of a man and woman in a revised constitution, ruling out gay marriage.
It is among several constitutional amendments proposed by Mr Putin, which are set to be put to a public vote.
Critics see the proposals as a move by Mr Putin to keep a hold on power after his presidential term ends in 2024.
The package includes a proclamation of Russians' faith in God and a ban on giving away any Russian territory.
The territorial amendment would strengthen Russia's hold on Crimea - a Ukrainian region it annexed in 2014 - and the Kuril Islands, disputed with Japan since World War Two, according to Vladimir Mashkov, a renowned actor-director involved in drafting the new constitution.
Why does Vladimir Putin suddenly feel the need to write all this into Russia's constitution?
It has less to do with reflecting current values in society and more to do with creating talking points that conceal the suspected chief reason behind the constitutional rewrite: providing a legal basis for President Putin to remain in a position of influence or power after 2024 - if not as president, then in some other role.
Among the proposed changes that get little mention in the state media here is the inclusion in the constitution of a little-known body called the State Council. It's believed this could be a possible future power base for Mr Putin. Other amendments will end up strengthening the power of the president.
But since Mr Putin has decided he wants Russians to vote on the proposals, he needs to find a way of getting people excited about the changes - and getting them to the ballot boxes on 22 April. That's where the populist slogans come in - and subjects like God, family and marriage - as well as promises to include in the constitution support for wages and pensions.
Mr Putin also proposed an amendment on "historical truth", to protect "the great achievement of the people in their defence of the Fatherland".
