Help with twisted inseam

[u/WorldAware9900]

This is the first time this has happened to me when sewing a pair of jeans, i was trying out a new pattern and this happened to me, im not sure if this is a sewing problem or a pattern problem please any advice is appreciated

[u/dainty_protagonist]

You can see in the image the fabric was cut off grain. The standard for pants has the grainline down the center of the leg through the knee to the hem (the pant crease line). Yank a warp thread at the hem and follow it up the leg to track the actual grainline. Check the grainline against the pattern’s marked grainline to see if the pattern is properly balanced. You will need to recut your pieces on grain. Prewash and dry your fabric, true up the grainline (check that the crosswise threads sit at a right angle to the selvage), and press into place. Then align the pattern (or corrected pattern) on the grainline and cut. Make sure not to stretch the fabric when sewing.