Well, not good..
If u have 'loose joints' ( elbows, fingers, shoulders etc.
) and have hyperextension ( recurvatum) @ both your knees it's not 'bad'just the way u are...! in my experience, people w/ hyperextension @ the knees occassionally have trouble w/jumping
sports( basketball, gymnastics
..)real problems w/ instability occur if they tear there acl( hopefully not!)again, the vast majority of people do well... Gl!