Short answer: yes.
The problem with reading symptoms on the internet is that it's so easy to relate them to non-specific symptoms which you may be having and these symptoms may be unconnected. It depends what type of heart disease you mean. Coronary heart disease
is generally seen in much older people but it can sometimes affect young people, especially if there is a strong family history.
Structural abnormalities of the heart including valvular disease can sometimes present later in life.
How old were your grandparents when they had strokes? If it's above the age of 55 (for men) and 65 (for women) then this isn't really significant as this can be considered part of the normal ageing process and is not really premature. Did your parents have high cholesterol
or other heart issues when they were in their 20s and 30s? If so, it's worth having your cholesterol levels checked. Make an appointment with your Doctor and he'll arrange this for you.
Grandparents are not first degree relatives either.
Excess weight, an unhealthy diet and lack of exercise will of course contribute to premature ageing. If you have health concerns, see your GP and he'll do some general tests.