It can take up to age 19 for complete foreskin retraction. 4% are born with retractable foreskin. Testosterone regulates the natural foreskin glans separation. One can be healthy having a non retracting foreskin. Many men are okay with this. So it is not a problem and no problem to fix. (many doctors term non retraction as a problem for citing a reason for circumcision and for circumcision itself. I was retractable at age 3-4. Boys usually play with their foreskins for pleasure. But nature also helps boys to naturally help themselves the spur along the separation of foreskin and glans by making it itch. (Yet another reason given to circumcise to stop manipulating the foreskin). The only person to attempt retraction is the boy himself. Best done in the warm bath pulling the foreskin gently back, when pulled forward using insertion of fingers to dilate (if possible). It is important to tell sons about retraction. Some boys who have not been told, when first all of a sudden retract are scared thinking it is broken. Even some are not aware of the possibility of retraction well into adulthood. Low dosage betasone cream can help with retraction. TLC-tugger now makes a dilator for the foreskin's orifice for those that can not get a finger in to help retract.
Smegma does not cause penile cancer. Though many doctors say it can there is no study done. Greeks have it right, smegma means nature's soap. There is no study on smegma because it then would show smegma to be beneficial and not cancer causing, yet another reason to circumcise would be gone.
We are born with variances. We know the thickness of dartos muscle varies. It is what keeps the foreskin tight to the glans, for protection of the whole, conserve warmth, constrict some movement when running, protect against frostbite and damaging UV rays on sensitive receptors. The tightness of scrotum means the tightness of foreskin. I believe a non retractile but fully separated foreskin/glans if not diseased or scarred, is just thicker than most dartos, a muscle that can be trained to be loose or tight. Men who restore their foreskins through stretching use retainers to train the muscle to keep forward just as some cultures train to keep the foreskin retracted.
FYI- The dartos muscle is striated longitudinal to the penis but as it approaches the tip, the muscle striates transitionally transverse so at the foreskin the dartos is fully transverse to the penis. Nature makes best use of the dartos in this way. This arrangement of muscle is lost to circumcision and can not be restored.
FYI- Cold/Taylor-the presence of smegma preputii is a rare finding; in a prospective examination of 4521 uncircumcised boys, only 0.5% had smegma.
FYI- Dr. John Taylor penile and heart researcher - Sexual Function of the Dartos Muscle (loosely):
Upon erection the Dartos muscle tenses creating a one-piece solid skin tube, where any action on the penile shaft is transferred to act on the erogenous Taylor's Ridged Band and through its loop to the Frenulum, this action it transferred to act on the erogenous Frenulum, together the male's sexual nexus. No action on the shaft is wasted on these sexual structures.
Circumcision always removes all of the erogenous Taylor's Ridged Band and part to all of it's connecting Frenulum. Having this hangman's noose of the male's sexual receptors missing no longer keeps the whole of the penile Dartos muscle tense. With tension gone, all action on the erect penile shaft is wasted to act on the Ridged Band and Frenulum. Action must be applied directly to the Frenulum remnant, if any remains.
Circumcision cuts off 65%-85% of the male's sexual receptors (85% when the frenulum is cut or scraped off infant). This leaves 15% sexual receptors located in the glans corona where it's overpowered by the more populous pain/thermal receptors, ratio 5% to 95%. It is this case that men report "If I felt anymore sensitivity, I think I would die of a heart attack!" (Larry David) Circumcision changes the way, means, and type of sensations felt. Circumcision sexually handicaps.
Consider- The bi-level locations of sexual receptors are located in the ridged band and juxtaposed in the corona. Together, circumferentially the amount of sexual receptors are constant though are inverse to each other going mid-ventral to dorsal. So at dorsal there are more sexual receptors in the glans than in the corresponding ridged band. Inverse to the mid ventral when there are more sexual receptors in the ridge band than the corona. Thus being unequal heightens awareness sensation. Like rubbing fingers of one hand against palm to fingers of the other hand and visa versa. Thus being bi-level located, the cutting off all the ridged band make for the perception of going from stereo to mono.