Courtesy of Ryan McCarthy (a descendant of Eugene McCarthy and his first wife Catherine Traynor), here’s a really nice studio portrait from about 1915 (taken at Perth, Lanark Co., Ontario):
Only two of the four subjects (the two in the middle) can be positively identified. The two people in the middle are half-brothers: the young child is James Francis McCarthy (born 1912), son of John Joseph McCarthy (1869-1923) and his second wife Annie Powell; and the young man who is holding the child is John Joseph McCarthy (born 1893), son of John Joseph McCarthy and his first wife Catherine O’Dea. The man on the far left is probably John Joseph McCarthy Senior. The man on the far right is unidentified, though a notation on the back of the photograph suggests he might be an O’Dea.