Ham and Ex are St. Bernard twins as well as Beans' nephews. Though naked in their debut, they are fully clothed in later appearances.
A note signed "Lizzie" asks Beans to watch them one day. One might infer this is their mother.
The dogs made their debut in "I Haven't Got a Hat". A year later, they reappeared in "The Phantom Ship". The two would also have the lead role in "The Fire Alarm". They had their final role in "Westward Whoa".