Robert Downey Jr shares rare photo of son Exton - as he talks about Indio's addiction

gave fans a

of his

this week, by sharing a sweet family photo on his Twitter account. The actor has been in Toronto recently to promote his upcoming drama,

, at the film festival, accompanied by his

and their eldest child. And as they prepared to return home, Robert posted a picture of the trio, captioned, "

"

© Photo: Twitter

Little Exton can been seen smiling for the camera, wearing a hat like his daddy, and sandwiched in-between his proud parents. In just two months he will be a big brother; Robert and Susan are

,

, in November. The picture coincides with an interview Robert recently gave to

in which he opened up about his

.The star spoke about his own

before his sobriety in 2002 – "Job one is get out of that cave. A lot of people do get out but don't change" – and also addressed the

.

Indio, his 20-year-old son with ex-wife

, was

in June."He's his mother's son and he's my son, and he's come up the chasm much quicker than we did," Robert told the magazine. "But that's typical in the Information Age; things get accelerated."He added, "

."