Not unless you know something about the linage.
You can pretty much tell if its Sativa or Indica or a Hybrid sometimes but there are thousands of strain's and crosses. I suggest you name it yourself and move on.
Another words just because its purple doesnt mean its Grandaddy Purple if you catch my drift.
Awesome. I remember growing some seeds i found in some good dank. Didnt know what strain it was so i named it RC Cola. The first two letters R and C is mine and the Wifes 1st letters in our 1st names,,the Cola because they were huge. I cloned it several times.