Downs syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21. It is characterized by certain physical and intellectual features.

Option 1 is correct as Downs syndrome is indeed a genetic disorder. It is caused by a chromosomal abnormality where an individual has three copies of chromosome 21 instead of the usual two.

Option 2 is incorrect. Downs syndrome does not cause early aging in individuals. However, individuals with Downs syndrome may exhibit some physical traits commonly associated with aging, such as wrinkles and slower physical development.

Option 3 is correct. Mental retardation is one of the characteristic features of Downs syndrome. It can range from mild to moderate in severity.

Option 4 is incorrect. While individuals with Downs syndrome may have certain physical characteristics, such as a furrowed tongue and an open mouth, it is not a defining feature of the condition. These physical traits may vary from person to person.

In summary, the correct answer is option 2, as it incorrectly states that Downs syndrome causes early aging.