Robert Downey Jr. for How to Talk to Girls? Robert Downey Jr. has joined the cast of How to Talk to Girls. According to reports, the actor has officially quit “Gravity,” the Alfonso Cuaron outer space survival thriller and is now circling this new project, an adaptation of a book by a 9-year-old boy revolving around advice on how to deal with the opposite sex. Girls was written by Alec Greven, then 9 years old, as a school project. It landed the boy a publishing deal and put him on talk shows across the country. Downey, along with wife and producing partner Susan Downey, would also come aboard as producers.