Sunetsugu Honekawa is Suneo's younger brother. He lives in New York with his uncle (who is single and raises him like a son). He is around seven or eight years old. The reason why he lives in New York instead of with his family is currently unknown.

In a 2007 episode Sunetsugu was shown to be arrogant towards Nobita, much like Suneo. His personality was changed to show him as a more well-mannered and naive person in later episodes, presumably signalling his redemption.

In the 2005 anime episode "Arigataya", Sunetsugu was shown with brown hair and smaller eyes, and did not resemble Suneo as much. He was remodeled for later episodes and currently strongly resembles his family members.

(Source: Doraemon Wiki)