The National Assembly is drafting a new constitution that will maintain the one-party system but aims to adapt the country to new social and economic times. The current one dates from 1976.
"In the constitution there is a section on rights in which LGBT people must be involved," Castro told AFP in an interview.
"Constitutions do not necessarily get down to specifics. They open doors so later we can talk about changing the legislative system."
Support of current president
After the Cuban revolution of 1959, homosexuals suffered repression and punishment. Fidel Castro eventually apologized for this and insisted it was not a systematic policy of the state.
As a member of the Cuban Communist Party, Mariela Castro works to teach leaders as well as everyday citizens about tolerance.
One of them was Miguel Diaz-Canel, who took over as president in April, ending decades of rule by the Castro brothers -- first Fidel and then his brother Raul. Diaz-Canel got tolerance education as a member of the party's youth wing.
"At one time he would go to Cenesex and attend our meeting, and we had a very productive dialogue," Castro said.
She said Cuban society has made progress on issues involving LGBT rights.
"Before, there was prejudice against talking about these things. Eleven years ago we started holding seminars about homophobia and trans-phobia. And that helped to pave the way for dialogue among the population," she said.
For the past decade Havana has hosted a gay rights parade called the Conga.
"There are people who are bothered by seeing LGBT people dressed up and having fun, and there are those who enjoy it," said Castro.
"We do not want to cause unease but rather instill interest in dialogue," she added.
And it is not just a matter of passing laws: in countries with same sex marriage there can still be high levels of violence against LGBT people, such as in Mexico.
"With marriages, did they stop that violence attitude? No. Bring on laws, of course, but we must work from a policy standpoint and in that we have not made enough progress," said Castro.
From June 25-29 Cenesex is holding a convention on sex education, orientation and therapy.
Erode the patricarchal state
Castro has recalled that since 1965 abortion has been legal in Cuba and is carried out for free.
"The goal was to save the lives of women and ensure their right to decide what they do with their body," she said.
But in Latin America, a misogynous mindset dating way back still predominates, according to Castro.
Even with women as president in some countries it has been hard to work for gender equality.
"They did not manage to bring about change. Not because the women did not want to but rather they faced very strong political opposition," Castro said.
Cuba also went through periods of resistance to women's rights -- "but we were lucky to have the leadership of Fidel Castro" who in 1960 created the Federation of Cuban Women, she said.
Cuba's national assembly has the highest proportion of women in the world, after that of Rwanda, she argued.
The work that began 60 years ago has helped erode the patriarchal state as the paradigm of power.
"We have not managed to overcome all the symbolic elements of the patriarchal state but we have weakened it."