How do surrogate mothers have someone else's biological child?

Is the child solely the biological child of the parents (not the surrogate mother)? How do the surrogate mother's DNA and traits not affect the baby?How do surrogate mothers have someone else's biological child?
Surrogates get the embryo of another couple implanted in their uterus. The spern and egg..ie where the DNA is found, is from two other people..therefore the surrogate merely act as an incubator.. her DNA has nothing to do with the emryo since it wasnt her egg used to creat said embryo.How do surrogate mothers have someone else's biological child?
Same way your child can have a different blood type from you. The DNA is nothing more than blue prints for the body. The placenta provides the nourishment to the embryo, and all the nourishment gets transformed inside the embryo for building a baby. Your DNA has no say what is happening in there.