It was inevitable that Casanova would father children, even though he never married. In Venice, this happened two times (at least as far as his memoirs attest to).
One near miss was with Caterina Capretta, the 14-year-old daughter of a merchant, who Casanova first met because her rotten brother wanted to dupe Casanova into lending (or giving) him money. Caterina was the bait. But the girl and the man fell in love. They ran foot races on Giudecca, they slid through nighttime waters in a gondola, they went masked to the theater, and they declared themselves married before God. But once Caterina’s father discovered that his daughter was seeing the notorious Casanova, he gave her 15 minutes to pack her bag before he sent her to a convent on Murano. But the damage had been done. She later miscarried and, rather miraculously, was able to hide the truth from the Mother Superior, with some help from a servant and another nun.
So I guess this child doesn’t quite count as Casanova’s child since it never had a chance to be born.
Caterina was now out of reach of Casanova. He took rooms on Murano to be near her, and was then propositioned by MM (probably Marina Morosini), another nun (in fact, the same one who kept Caterina’s secret). Of course, it wasn’t simple for Casanova to see either woman, and while the affairs lasted for a while, they didn’t last forever. Eventually one rainy and sad night, when Casavova was prevented from seeing these lovers, his head was turned by his maid Tonina, clad only in her nightshift. They set up house, and Casanova claims these were some of the happiest days he lived. Tonina became pregnant, and then Casanova’s friend, the English resident, took a fancy to the girl. He offered to take her as his mistress, pregnant as she was, give her a home, pay to raise the child, and later give her a dowry. Tonina, a practical girl, agreed, and Casanova acquiesed to these bittersweet terms in order to give the girl a chance at a later dowry, which he could never provide. He never tells us anything else about this child.
On another occasion, when Casanova had been away from Venice for a while, he returned to find that his old friend Teresa Imer was in town. The two had grown up around the corner from each other, and their parents all acted in the San Samuele theater together. (In fact, biographer Judith Summers contends that these two may have had the same father since Casanova’s mother is known to have had a long affair with Giuseppe Imer.) When Casanova learned that Teresa was in town, he went to visit her, and he tells us that their last hour together was the one that counted. They created Sophie, their daughter whose existence Casanova didn’t learn about until many years later, in Amsterdam. He offered to educate the girl, but Teresa wouldn’t part with her. Casanova later did pay for Sophie’s education in London, though, and she was one of his only children that he developed a relationship with.
There is one more pregnancy related to Casanova that is worth noting. Casanova’s friend Andrea Memmo carried on a lengthy affair with Giustiniana Wynne, and Casanova met the beauty a number of times in Venice. But it wasn’t until they ran into each other in Paris when Giustiniana implored Casanova to help her procure an abortion for her unwanted pregnancy. It’s not entirely clear that the child was Memmo’s. This was risky business, because procuring an abortion could carry the death penalty. A meeting with a midwife proved futile, so Casanova made up a concoction and a story about an “aroph” or a mixture that would induce an abortion. It worked best when applied directly with a tubular instrument, and he offered his personal services. Giustiniana, amazingly, agreed, and they had to apply the aroph a number of times to make sure it worked. It didn’t, and Casanova ultimately helped the girl find a convent where she could bring the baby to term. Though this wasn’t Casanova’s baby, it’s still a pregnancy where he played a vital part.
Casanova’s memoirs tell stories of other children he sired, but here I focus on Venice, so this is all you get!