According to a source, the former Suits star, 36, cares deeply about being a "modern woman" concerned about important issues such as the distribution of the planet’s resources.
"Meghan is big on humanitarian work and appearing to care about the earth," the insider told Radar.
"She feels having what she thinks of as a 'sustainable family' would fly in the face of this, so she wants to limit the number of children she and Harry have to just two."
The royal spy said that Markle "knows that there will be pressure from the public and royal family" for her and Harry, 33, to "match" his brother Prince William and his wife Kate Middleton in having at least three kids.
"But she has her mind made up it wouldn't be the right look for her – and she is known for getting her own way in life," the source dished.
The former Suits star, like many from Hollywood, is interested in social causes.
Markle has established her humanitarian credentials by working as a global ambassador for World Vision, advocate for the United Nations and a campaigner for gender equality. She made her first public appearance with Prince Harry at the charitable Invictus Games.
Due to her work promoting women’s rights, the insider said Markle, a divorcee, is "fiercely protective of her right to choose what she does with her body."
Also, William, 35, and Duchess Middleton, 36, were slammed for having three children by some who believe it's not environmentally friendly and "unfair" to poor families as the British can only now claim tax credits for their first two children.
William and Kate recently had their third child, baby boy Louis, despite being urged in an open letter by Having Kids, an organization that promotes smaller families, to "lead by example" and not add to their family.
Meanwhile, Markle, who will turn 37 in August, is a fitness fan and is reportedly hoping to have twins, "as she feels she will be able to get back to her ideal body shape if she does not have two separate pregnancies."
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